Log breakdown by sawing can be viewed as a multi-phase process that converts logs into boards by a series of cutting operations. In the primary phase, logs are sawn into s labs of wood known as flitches or cants. These are further processed by secondary operations, that resaw, edge (cut lengthwise) and trim (cut widthwise) the raw material, resulting in the manufacture of the board product whose value is influenced by its composite dimensions and quality (as indicated by a grade). Board grade is in turn determined by the number, type, size, and location of defects. Owing to its biological origins, each log, and subsequent board, is unique. Furthermore, as each sawmill, and processing centre within the mill, has a unique configuration, the problem of determining how each log entering a mill should be sawn is very complex. Effective computer simulation of log breakdown processes must therefore entail detailed descriptions of both geometry and quality of individual logs. Appropriate strategies at each breakdown phase are also required. In this thesis models for emulating log breakdown are developed in conjunction with an existing sawing simulation system which requires, as input, detailed three-dimensional descriptions of both internal and external log characteristics. Models based on heuristic and enumerative procedures, and those based upon the principles of dynamic programming (DP) are formulated, encoded, and compared. Log breakdown phases are considered both independently and in a combined integrated approach-working backwards from the board product through to the primary log breakdown phase. This approach permits methodology developed for the later processes to be embedded within the primary phase thus permitting the determination of a global rather than local solution to the log breakdown problem whose objective is to seek the highest possible solution quality within the minimum possible time. Simulation results indicate that solution quality and processing speeds are influenced by both solution methodology and degree of data complexity. When the structure of either factor is simplified, solutions are generated more rapidly-but with an accompanying reduction in solution quality. A promising compromise that combines DP techniques with mathematical functions based on a subset of the original data is presented. / Subscription resource available via Digital Dissertations only.

Log breakdown by sawing can be viewed as a multi-phase process that converts logs into boards by a series of cutting operations. In the primary phase, logs are sawn into s labs of wood known as flitches or cants. These are further processed by secondary operations, that resaw, edge (cut lengthwise) and trim (cut widthwise) the raw material, resulting in the manufacture of the board product whose value is influenced by its composite dimensions and quality (as indicated by a grade). Board grade is in turn determined by the number, type, size, and location of defects. Owing to its biological origins, each log, and subsequent board, is unique. Furthermore, as each sawmill, and processing centre within the mill, has a unique configuration, the problem of determining how each log entering a mill should be sawn is very complex. Effective computer simulation of log breakdown processes must therefore entail detailed descriptions of both geometry and quality of individual logs. Appropriate strategies at each breakdown phase are also required. In this thesis models for emulating log breakdown are developed in conjunction with an existing sawing simulation system which requires, as input, detailed three-dimensional descriptions of both internal and external log characteristics. Models based on heuristic and enumerative procedures, and those based upon the principles of dynamic programming (DP) are formulated, encoded, and compared. Log breakdown phases are considered both independently and in a combined integrated approach-working backwards from the board product through to the primary log breakdown phase. This approach permits methodology developed for the later processes to be embedded within the primary phase thus permitting the determination of a global rather than local solution to the log breakdown problem whose objective is to seek the highest possible solution quality within the minimum possible time. Simulation results indicate that solution quality and processing speeds are influenced by both solution methodology and degree of data complexity. When the structure of either factor is simplified, solutions are generated more rapidly-but with an accompanying reduction in solution quality. A promising compromise that combines DP techniques with mathematical functions based on a subset of the original data is presented. / Subscription resource available via Digital Dissertations only.

Log breakdown by sawing can be viewed as a multi-phase process that converts logs into boards by a series of cutting operations. In the primary phase, logs are sawn into s labs of wood known as flitches or cants. These are further processed by secondary operations, that resaw, edge (cut lengthwise) and trim (cut widthwise) the raw material, resulting in the manufacture of the board product whose value is influenced by its composite dimensions and quality (as indicated by a grade). Board grade is in turn determined by the number, type, size, and location of defects. Owing to its biological origins, each log, and subsequent board, is unique. Furthermore, as each sawmill, and processing centre within the mill, has a unique configuration, the problem of determining how each log entering a mill should be sawn is very complex. Effective computer simulation of log breakdown processes must therefore entail detailed descriptions of both geometry and quality of individual logs. Appropriate strategies at each breakdown phase are also required. In this thesis models for emulating log breakdown are developed in conjunction with an existing sawing simulation system which requires, as input, detailed three-dimensional descriptions of both internal and external log characteristics. Models based on heuristic and enumerative procedures, and those based upon the principles of dynamic programming (DP) are formulated, encoded, and compared. Log breakdown phases are considered both independently and in a combined integrated approach-working backwards from the board product through to the primary log breakdown phase. This approach permits methodology developed for the later processes to be embedded within the primary phase thus permitting the determination of a global rather than local solution to the log breakdown problem whose objective is to seek the highest possible solution quality within the minimum possible time. Simulation results indicate that solution quality and processing speeds are influenced by both solution methodology and degree of data complexity. When the structure of either factor is simplified, solutions are generated more rapidly-but with an accompanying reduction in solution quality. A promising compromise that combines DP techniques with mathematical functions based on a subset of the original data is presented. / Subscription resource available via Digital Dissertations only.

Log breakdown by sawing can be viewed as a multi-phase process that converts logs into boards by a series of cutting operations. In the primary phase, logs are sawn into s labs of wood known as flitches or cants. These are further processed by secondary operations, that resaw, edge (cut lengthwise) and trim (cut widthwise) the raw material, resulting in the manufacture of the board product whose value is influenced by its composite dimensions and quality (as indicated by a grade). Board grade is in turn determined by the number, type, size, and location of defects. Owing to its biological origins, each log, and subsequent board, is unique. Furthermore, as each sawmill, and processing centre within the mill, has a unique configuration, the problem of determining how each log entering a mill should be sawn is very complex. Effective computer simulation of log breakdown processes must therefore entail detailed descriptions of both geometry and quality of individual logs. Appropriate strategies at each breakdown phase are also required. In this thesis models for emulating log breakdown are developed in conjunction with an existing sawing simulation system which requires, as input, detailed three-dimensional descriptions of both internal and external log characteristics. Models based on heuristic and enumerative procedures, and those based upon the principles of dynamic programming (DP) are formulated, encoded, and compared. Log breakdown phases are considered both independently and in a combined integrated approach-working backwards from the board product through to the primary log breakdown phase. This approach permits methodology developed for the later processes to be embedded within the primary phase thus permitting the determination of a global rather than local solution to the log breakdown problem whose objective is to seek the highest possible solution quality within the minimum possible time. Simulation results indicate that solution quality and processing speeds are influenced by both solution methodology and degree of data complexity. When the structure of either factor is simplified, solutions are generated more rapidly-but with an accompanying reduction in solution quality. A promising compromise that combines DP techniques with mathematical functions based on a subset of the original data is presented. / Subscription resource available via Digital Dissertations only.

Log breakdown by sawing can be viewed as a multi-phase process that converts logs into boards by a series of cutting operations. In the primary phase, logs are sawn into s labs of wood known as flitches or cants. These are further processed by secondary operations, that resaw, edge (cut lengthwise) and trim (cut widthwise) the raw material, resulting in the manufacture of the board product whose value is influenced by its composite dimensions and quality (as indicated by a grade). Board grade is in turn determined by the number, type, size, and location of defects. Owing to its biological origins, each log, and subsequent board, is unique. Furthermore, as each sawmill, and processing centre within the mill, has a unique configuration, the problem of determining how each log entering a mill should be sawn is very complex. Effective computer simulation of log breakdown processes must therefore entail detailed descriptions of both geometry and quality of individual logs. Appropriate strategies at each breakdown phase are also required. In this thesis models for emulating log breakdown are developed in conjunction with an existing sawing simulation system which requires, as input, detailed three-dimensional descriptions of both internal and external log characteristics. Models based on heuristic and enumerative procedures, and those based upon the principles of dynamic programming (DP) are formulated, encoded, and compared. Log breakdown phases are considered both independently and in a combined integrated approach-working backwards from the board product through to the primary log breakdown phase. This approach permits methodology developed for the later processes to be embedded within the primary phase thus permitting the determination of a global rather than local solution to the log breakdown problem whose objective is to seek the highest possible solution quality within the minimum possible time. Simulation results indicate that solution quality and processing speeds are influenced by both solution methodology and degree of data complexity. When the structure of either factor is simplified, solutions are generated more rapidly-but with an accompanying reduction in solution quality. A promising compromise that combines DP techniques with mathematical functions based on a subset of the original data is presented. / Subscription resource available via Digital Dissertations only.

Wood chemical treatment is an important process in the wood industry, in that such treatment alters the properties of wood so that a variety of wood-based products can be fabricated with enhanced performance. However, wood's complex composition and structure make it difficult to achieve consistent and controllable treatment. An innovative self-flowing process presented for the chemical treatment of wood is inspired by liquid transportation in trees. Effectiveness of the self-flowing process is evaluated and compared to conventional immersion and vacuum wood treatment methods. The self-flowing process allows a more uniform wood treatment compared to that from the immersion and vacuum pressure methods. Lignin content after self-flowing delignification is below 5% with a standard deviation of 0.7, compared to ~20% with a standard deviation of 8 for both immersion and vacuum pressure methods. The self-flowing process allows 100% chemical impregnation depth for the preservation treatment. A mathematical model was developed to simulate the self-flowing process. This model can accurately predict the treatment time required for achieving desired results under various conditions, including temperature, wood density, and liquid properties. This work demonstrates that the self-flowing treatment is a highly efficient, cost-effective, and reliable method in wood preservation and modification industries.